A society that provides a basic income may also need an ethic that encourages not-for-profit activity, creativity and community involvement. The "Universal Job" is just to be a healthy human being and make your community - no matter if it's the global civilization or just your own family - "richer" in a non monetary sense.
It seems to me that this would be a much more efficient kind of "employment" for the public good than paying people to do some useless bureaucratic work.
If technology could be used to automate the whole chain of touch points and thus remove the need for human incentives to get things produced why insist on an old paradigm with what would mostly be the most shitty jobs you could find.
That seems like using technology for the opposite of what it's good for and for insisting on an very undesirable part of being alive.
Using this system, we ensure that no single capital-holder controls too much mining power over the currency. Every working man is judged on his merits, using a system that is hard for any one actor to parallelize or scale. So many many distinct actors work to secure the underlying currency, and it is safer against large banks or governments.
You take $10 of taxes and $10 of work ($20 total), and give $10 to the worker.
But maybe 50% waste is still better by order of magnitude than average government projects.
Roll the dice, use your government-approved paper to calculate the hash, and claim your prize if you're the first winner. Prizes and difficulty are designed to statistically provide a target $/hour.